Poor service

I took out a contract with Cell C 2014 and another one 2015. I paid off one of my contracts because I wanted a new phone but instead the money which I paid was allocated to the new contact instead of the contract that was to be cancelled. So I have to pay again another money to settle that contract. This year I paid off another contract and the money wasn't allocated to another account and my installment was high. When I called to query no one had the answers of why the amount was high I wasn't being transferred and still no solution. I want to cancel the current contract with cell c I'm not satisfied with their service. They never have answers when it comes to their charges